738 research outputs found
Induced Defects in Carbonaceous Materials for Hydrogen Storage
The induced defects in carbonaceous materials for hydrogen storage were studied. The effect of exfoliation was studied and the graphite nanofibers (GNF) diameter before and after exfoliation was quantified. Thermal decomposition of the GNF before and after sulfuric/nitric acid exfoliation indicated a clear loss of thermal stability. GNF exfoliation enhanced the hydrogen uptake by a factor of five compared to the untreated GNF. The amorphous carbon was reactive than GNF, and decomposed before the GNF. The higher pretreatment temperature was intended to preferentially remove amorphous carbon leaving a higher purity of exfoliated GNF
Adapting SAM for CDF
The CDF and D0 experiments probe the high-energy frontier and as they do so
have accumulated hundreds of Terabytes of data on the way to petabytes of data
over the next two years. The experiments have made a commitment to use the
developing Grid based on the SAM system to handle these data. The D0 SAM has
been extended for use in CDF as common patterns of design emerged to meet the
similar requirements of these experiments. The process by which the merger was
achieved is explained with particular emphasis on lessons learned concerning
the database design patterns plus realization of the use cases.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, pdf format, TUAT00
Atomic mass dependence of \Xi^- and \overline{\Xi}^+ production in central 250 GeV \pi^- nucleon interactions
We present the first measurement of the atomic mass dependence of central
\Xi^- and \overline{\Xi}^+ production. It is measured using a sample of 22,459
\Xi^-'s and \overline{\Xi}^+'s produced in collisions between a 250 GeV \pi^-
beam and targets of beryllium, aluminum, copper, and tungsten. The relative
cross sections are fit to the two parameter function \sigma_0 A^\alpha, where A
is the atomic mass. We measure \alpha = 0.924+-0.020+-0.025, for Feynman-x in
the range -0.09 < x_F < 0.15.Comment: 10 pages, revtex, 2 figures, submitted to Phys. Rev.
Measurement of the Boson Mass
A measurement of the mass of the boson is presented based on a sample of
5982 decays observed in collisions at
= 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a
fit to the transverse mass spectrum, combined with measurements of the
boson mass, the boson mass is measured to be .Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures
(submitted to PRL
Search for First Generation Scalar Leptoquark Pairs in ppbar Collisions at sqrt(s)=1.8 TeV
We have searched for first generation scalar leptoquark (LQ) pairs in the
enu+jets channel using ppbar collider data (integrated luminosity= 115 pb^-1)
collected by the DZero experiment at the Fermilab Tevatron during 1992-96. The
analysis yields no candidate events. We combine the results with those from the
ee+jets and nunu+jets channels to obtain 95% confidence level (CL) upper limits
on the LQ pair production cross section as a function of mass and of beta, the
branching fraction to a charged lepton. Comparing with the next-to-leading
order theory, we set 95% CL lower limits on the LQ mass of 225, 204, and 79
GeV/c^2 for beta=1, 1/2, and 0, respectively.Comment: 14 pages, 4 figures, submitted to Physical Review Letters Replaced to
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Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV
Inclusive dijet production at large pseudorapidity intervals (delta_eta)
between the two jets has been suggested as a regime for observing BFKL
dynamics. We have measured the dijet cross section for large delta_eta in ppbar
collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic
cross section increases strongly with the size of delta_eta. The observed
growth is even stronger than expected on the basis of BFKL resummation in the
leading logarithmic approximation. The growth of the partonic cross section can
be accommodated with an effective BFKL intercept of
a_{BFKL}(20GeV)=1.65+/-0.07.Comment: Published in Physical Review Letter
Measurement of the Top Quark Mass Using Dilepton Events
The D0 collaboration has performed a measurement of the top quark mass based
on six candidate events for the process t tbar -> b W+ bbar W-, where the W
bosons decay to e nu or mu nu. This sample was collected during an exposure of
the D0 detector to an integrated luminosity of 125 pb^-1 of sqrt(s)=1.8 TeV
p-pbar collisions. We obtain mt = 168.4 +- 12.3 (stat) +- 3.7 (sys) GeV/c^2,
consistent with the measurement obtained using single-lepton events.
Combination of the single-lepton and dilepton results yields mt = 172.0 +- 7.5
GeV/c^2.Comment: 12 pages, 3 figure
Search for Top Squark Pair Production in the Dielectron Channel
This report describes the first search for top squark pair production in the
channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using
74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence
level upper limit on sigma*B is presented. The limit is above the theoretical
expectation for sigma*B for this process, but does show the sensitivity of the
current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report
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